Increase in deoxyribonuclease activity in uraemic lymphocytes is caused by the cleavage of the largest polymerase I subunit.

Deoxyribonucleases and DNA-dependent RNA polymerase activities in T and B lymphocytes isolated from patients with chronic renal failure and control subjects were studied. The data clearly shows that the nuclease activity in T and B cells isolated from uraemic patients is remarkably enhanced when compared to the control cells. Concomitant with the enhancement in enzyme activity, the reduction in RNA polymerase I activity and quantity was observed. It was found that the increase in nuclease activity and quantity was limited to the group of relatively small nucleases with molecular weights ranging from 14 kDa to 18 kDa. It has been reported previously that these nucleases are among the cleavage products of the largest subunit of DNA-dependent RNA polymerase I. Thus we suggest that the depressed metabolic activity is a characteristic feature of the uraemic lymphocyte cells and the observed increased in DNase activity in those cells is a result of polymerase I degradation.